Please use this identifier to cite or link to this item: http://hdl.handle.net/2440/23615
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Type: Journal article
Title: Determining reproductive parameters for population assessments of chondrichthyan species with asynchronous ovulation and parturition: piked spurdog (Squalus megalops) as a case study
Author: Braccini, J.
Gillanders, B.
Walker, T.
Citation: Marine and Freshwater Research, 2006; 57(1):105-119
Publisher: C S I R O Publishing
Issue Date: 2006
ISSN: 1323-1650
Statement of
Responsibility: 
J. Matías Braccini, Bronwyn M. Gillanders A and Terence I. Walker
Abstract: Population assessments of chondrichthyan species require several key parameters of their reproductive biology, which were estimated for Squalus megalops (Macleay, 1881). Length-at-maturity differed depending on the criterion adopted for defining maturity. In the case of males, length-at-maturity was smallest when condition of seminal vesicles was adopted as a maturity criterion. For females, length-at-maturity was smallest when the largest follicle diameter >3 mm was adopted as the criterion for maturity; this was appropriate only as an indicator of the onset of maturity. Mature males are capable of mating throughout the year. Females have a continuous asynchronous reproductive cycle. The sex ratio of embryos is 1 : 1 and litter size and near-term embryo length increase with maternal length. Females have an ovarian cycle and gestation period of two years. This was reflected in the differences found between the maturity and maternity ogives. Although all females are mature at 600 mm, only 50% of them contribute to annual recruitment each year. Hence, for chondrichthyan species with reproductive cycles of two, three or more years, if maturity ogives are used in population assessments instead of maternity ogives, the models will overestimate recruitment rates.
Keywords: asynchrony; Australia; reproduction
Rights: © CSIRO 2006
RMID: 0020060083
DOI: 10.1071/MF05076
Appears in Collections:Earth and Environmental Sciences publications
Environment Institute Leaders publications

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